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California Sgional Water Quality Cc*rol Board
<br /> Central Valley Region
<br /> Katherine Hart, Chair 0
<br /> Linda S. Adams Arnold
<br /> Secretary for 11020 Sun Center Drive#200, Rancho Cordova, Californiaqs"
<br /> Schwarzenegger
<br /> Environmental Phone (916)464-3291 • FAX(916 Governor
<br /> �
<br /> Protection http://www.waterboards.ca.gov II
<br /> 6 April 2010
<br /> Ms. Jennifer Sedlachek
<br /> ExxonMobil Environmental Services CompanyR
<br /> 4096 Piedmont Ave, #194
<br /> Oakland, CA 94611
<br /> DOCUMENT REVIEW, FORMER MOBIL STATION 99CAS(AKA MARLER PROPERTY,
<br /> AKA JH GRIFFIN MOBIL SERVICE), 75 EAST ALPINE AVENUE, STOCKTON,
<br /> SAN JOAQUIN COUNTY(CASE# 390857)
<br /> I reviewed the Corrective Action Plan (CAP), received 29 March 2010 from your consultant ETIC
<br /> Engineering, Inc. (ETIC). The CAP evaluated four remedial alternatives in a feasibility study for
<br /> reduction of toxicity, plume mobility, and volume of contaminants; technical feasibility; and cost.
<br /> The CAP states monitored natural attenuation, while the most cost effective, would not prevent
<br /> downgradient plume migration, would not address contaminant mass reduction, and would require the
<br /> most time to complete. Groundwater pump and treat would be effective based on hydraulic
<br /> conductivity, but would not address soil contamination in unsaturated and vadose zones. Soil vapor
<br /> extraction (SVE) would be effective for mass reduction in unsaturated soil, but would not address
<br /> groundwater contamination or plume mobility. Dual phase extraction (DPE), for soil vapor, shallow
<br /> groundwater and liquid phase hydrocarbons (if present), in conjunction with SVE, would be effective for
<br /> soil and groundwater, and is the recommended remedial alternative. The proposed DPE/SVE (co-
<br /> extraction) system would use existing vapor extraction wells (VEW-1 through VEW-4) for soil only SVE
<br /> and apply a high vacuum by means of a stinger to the existing groundwater extraction wells (EX-1 and
<br /> EX-2), to lower the water table and expose petroleum hydrocarbons to vapor and water/liquid phase
<br /> hydrocarbons extraction. Project tasks to be completed upon Regional Board approval include design,
<br /> permitting, installation, and operations and maintenance of a co-extraction system.
<br /> The CAP recommendation for the co-extraction treatment system is approved. Please provide a work
<br /> plan containing the proposed treatment system design elements (plans and specifications, operations
<br /> and maintenance manual), and a schedule for the installation and startup of the co-extraction treatment
<br /> system by 20 May 2010. If you have any questions, you may contact me at (916) 464-4615, or by
<br /> e ail at jbarto waterboards.ca.gov.
<br /> AMES L. L. BARYON, P.G.
<br /> Engineering Geologist
<br /> cc: Ms. Carmen Harms, SWRCB, UST Cleanup Fund, OSCA Account, Sacramento
<br /> Mr. Nuel Henderson, San Joaquin County Environmental Health Department, Stockton
<br /> Mr. Duane and Ms. Wendy Berdt, Guido Segarini Trust, PO Box 1810, Aptos 95001
<br /> Ms. Theresa Marler, 14245 Lora Drive, #16, Los Gatos, CA 95030
<br /> Mr. Erik Appel, ETIC Engineering, 2285 Morello Avenue, Pleasant Hill 94523
<br /> California Environmental Protection Agency
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